Preparation and properties of catalyzed polyimide/dicyanate semi‐interpenetrating networks for polymer gas membrane with suppressed CO₂‐plasticization

Abstract

ABSTRACT:The work presents an approach to reduce the plasticization of polymeric membranes caused by condensable gases, and particularly the effect of plasticization caused on polyimides by CO 2 at high pressure. A technical polyimide, Matrimid V R , was chosen as a reference of polyimide membrane and the approach applied consisted of incorporating reactive oligomers to have cross-linkable mixed systems, which do not plasticize at high CO 2 pressure. Films of semi-interpenetrating networks (semi-IPNs) based on Matrimid V R and phenolphthalein dicyanate as cross-linking monomer in ratios 90/10, 80/20, and 70/30, were prepared using a catalyst to lower the curing temperature from 280 to 180 C. Semi-IPNs properties such as thermal stability, mechanical properties, glass transition temperatures, or density were measured to characterize the films and were correlated with the dicyanate monomer content. The CO 2 gas permeation behavior of the three semi-IPNs was studied using a CO 2 feed pressure ranging from 1 to 30 atm. The gas separation properties were mainly explained attending to the density of the films, which depended on the dicyanate content used. In the three catalyzed semi-IPNs, the CO 2 permeability coefficients remained almost constant all along the investigated range of CO 2 pressure while Matrimid

Incorporation of carbon nanofibers into a Matrimid polymer matrix: Effects on the gas permeability and selectivity properties

“…From the differential scanning calorimetry data, the glass‐transition temperature of the neat Matrimid was found to be 312.2 °C; this matched the literature value . (a), Moreover, all of the Matrimid–CNF composite showed glass‐transition temperatures near that of the pristine polymeric membrane (Table S1, Supporting Information, and Figure S) without any significant change. This showed that no chemical bonding was present between the CNFs and Matrimid in the Matrimid–CNF composites.…”

“…The mechanical properties of the Matrimid–CNF composite membranes were characterized by their Young's modulus, tensile stress, and extension at break values (Figure and Table S2, Supporting Information, ESI). The pristine Matrimid membrane showed nearly the same mechanical properties as reported earlier . However, the Matrimid–CNF composite membranes exhibited improvements in their mechanical properties with increasing CNF loading .…”

“…(a) TGA of the pristine Matrimid and Matrimid–CNF composite showed that thermal decomposition occurred in one step beginning at 495 °C, and the mass loss curve remained stable below 500 °C. However, it decreased rapidly above 500 °C . This suggested that the addition of CNFs in the polymer matrix did not deteriorate the thermal stability of the composite membrane.…”

Approaches to Suppress CO2-Induced Plasticization of Polyimide Membranes in Gas Separation Applications

“…Chemical structures of DCFT and DCFT-resin are shown in Figure 16. DCFT-modified membranes did not show any signs of plasticization in CO 2 feed pressures ranging from 1 to 30 atm [71]. Dicyanate cyclotrimerized into a uniform three-dimensional network of oxygen-linked triazine rings (cyanurate ester resin).…”